This invention pertains to a dental impression tray and a method of using the same to effect maximum curing by polymerization of impression material to form a negative impression of at least a part of dental anatomy in an oral cavity, the polymerization being effected by visible actinic light rays applied to the tray and impression material therein while the tray and said material are held firmly pressed against the dental anatomy which is to be reproduced in the form of a model or otherwise.
In general, for many years, it has been common practice in dentistry to form a model or cast of dental anatomy in the oral cavity of a patient by utilizing a suitable size and shape of a dental impression tray into which a predetermined amount of settable impression material is placed for manual impressment against the anatomy, such as a full or partial gum, with or without teeth. Normally, an appreciable amount of time is required to effect, by currently used activators and otherwise, suitable curing of presently available impression material into an elastomeric form having permanent memory. This technique necessarily monopolizes the full time of a denist or assiatant for the required period of curing time and during which, no other activities can be undertaken by the dentist or assistant.
Dental impression trays have been used for many years to contain pastes, for example, during the taking of impression of oral tissues or dental anatomy. Usually these trays are of metal and exist in a variety of shapes and sizes suitable for various situations. In recent years plastics have been substituted for metal, particularly for single use so as to be disposable. Some of these trays have been fitted with coolant systems for hardening pastes into gels but, in most instances, the viscous pastes are converted to elastic or rubbery condition by a reaction initiated by the mixing of two components immediately before the material is placed in the tray.
One recurrent problem with presently used dental impression trays is that the gelatinous or elastic material requires an integral non-distorting foundation. Adhesion of the elastomers to trays has been achieved by either perforating the trays or the use of adhesives.
Another problem with existing impression trays and taking impressions is that a significant amount of the mouth area is being covered by a large object for a long period of time--up to fifteen minutes, for example. The natural human reflex action in this situation is to gag, resulting in changing the contours of some of the tissue and musculature which was to be reproduced while static. Also, with the passage of several minutes times, salivation occurs from glands located near the impression area and these fluids affect the quality of impression reproduction.
A recent dental development has occurred in the area of restoratives and sealants where actinic radiation has been used in conjunction with phototsensitive accelerators to initiate prompt and rapid polymerization precisely when the dentist is ready with the patient. Heretofore, however, radiation curing has not been applied to elastomers, to large areas, or to materials needing to be confined in a radiation-conducting vehicle.
Particularly for purposes of shortening the time required to transform such impression material into a practical permanent elastomeric form having memory, and to avoid mixing a plurality of ingredients to form the material, the present invention has been conceived and reduced to practice by devising a novel type of impression tray with which harmless visible actinic light is used to effect curing the material by polymerizing novel impression material comprising the subject matter of one or more companion patent applications filed on even date herewith and assigned to the same assignee as the instant invention.